The U.S. is providing more arms and training to the moderate rebels in Syria, under a growing secret program run by the CIA in Jordan. Sources tell NPR that secret program could be supplemented by a more public effort in the coming months involving American military trainers.

The change in strategy comes as the White House sees Syrian leader Bashar Assad growing in strength, and continuing to strike rebel strongholds.

Another factor: Russian leaders appear unwilling to help end the three-year-old civil war and are continuing to provide weapons to Assad. Finally, al-Qaida fighters and their allies are expanding in Syria, a development that some believe could threaten the U.S. homeland.